Motor-driven tool



March 27, 1951 K C, ATK|N 2,546,846

MOTOR-DRIVEN TOOL Filed Nov. l, 1947 Patented Mar. 27, 1951 MOTORHDRIVEN TOOL Kenneth. C. Atkin, 4Muskegon, Mich.;v assignor'to i Clarke Sanding Machine Company, Muskegon, Mich., ra `corporation of Michigan.,

Application November 1, 19472' Serial'N: 783,607?

3.Gla,ms.

.' This':` invention relates: tof-.a Y newA and yimproved 'motorrfdriventool and liasifory. one of its-principal ,objects the'provision' ofimeans in a'liousingtherefor to.'acceleratezdissipation of motor heat;

, Ani' important i object' of this invention isto 'providein acompact motorfdriven hand-manipu- .latedztooLY means'forigeiciently cooling the motor without:producingfsuction' in the gear housing andrelieve; the'motoroi the objectionable suction-load.'-

Another important object of this invention is the. provision ofcoolingfan means forv drawing over the=motorrof aportable power-driven tooland iorv avoiding the setting up ofundesirable aix, currents at the vdriven tool.

A further; object of this-invention is-toV provide meansiin` the.constructionv ofthe housingof a powerrdriven toolwhcreby airl discharged through openings' in thel housing is directed. laterally.

away;y from Vthe housing. Y

' Anstill: further object ofthis` invention is.- to `prin/idemeans` in a motor-driven-tool which will fcausequickdissipation'of heat created bythe driving motor.

Another and stillfurther object is. to provide anovel-ian construction foruse in combination with yhousings of power-driven tools in which the fan y'creates air currents in the motor portion of the housing and is barred from setting up air currents.` in the tool portion of the housing.

Other and further importantV objects will be.- comei apparentiromthe disclosuresA inthe fol.- lowing specication and Aaccompanying drawing.

In the drawing:

Figurel is a side elevational View of the portablemotor-driven tool of .this invention.

Figure 2. is an Venlarged-view. similar to Figure liwith .portions thereof .in section to showinterior construction.

Figure. 3. is a sectional view taken on ,the vline f3e-3- ofl `figure 2=With the. motor cooling fan re.-

moved.

Figure 4 is a perspectiveview ofainid' por- .tionoffthe housingasishown-inEigures land 2.

Figure, is adiagram'rnatic.illustration oifthe cooling fan andit's housing, showing the. spiral .passagesthrough which air is discharged. Assliown inthe drawing:

The. reference numeral ID indicates. generally ashousing fora portable power-driven toolillustrated in Figures l and 2.- The housing lis elon.- gatedandin .normal use is. disposed vertically. A handle II .isfintegralwithrthe.housing I and eX.- tends` laterally therefrom to enablev an operator tocasily-move-the powerfdriven tool to. any de.- f

sired .location -andto effect tool operation.

'llfieupper^ portion. I2. of the housing Iii carries anelectricmotor or thelike I3..and thelowerpor- I 4'- of 'i the-Y housing. I 0i,- carries ,-gearz means..y i5 for. imparting. motor rotational. driveto a.l tool.

. 2- 'Ihe .fdravving;discloses.` the ftool as-.fa flexible plate li'made: offjrubber; .synthetic .rubber or some like material;A 'A1 hub II of: the flexibleY plate: is

equipped:with an vvintegrally attached; metal core I Biwhichfis-removably attachedto va driven sha-ft lvprojecting downwardlyfromlthe bottom of Athe housingjl Aby;rneans.'=of ascrew orathe Ylike 2G11.V A frustoeconical member- 2 I ts within aconicalshaped recess-22 in the center. of. the bottom of the-.ilexible plate I6.y Sandpaperror bufng sheets may be'attached. to the flexible plate leasrvvork engaging surfaces.. The;screw-2 and the cone section-2l' are removedand a-correspondingcir= cular sheet ofsandpaper.orftheflikeZSds placed facewdownwa-rdly on 'theunderside of the flexible platefIii:` Theconicalfsleeve'Zl:is then pushed up centrally thereof ,causingthe-paperto deiorm into theconica-lrecess` 22.. The screwhisthen reinserted thus holdinggthe conical sleeve 2.-I and thefsandpaperr sheet 23 againstexible. plate" I6 and'athe entire assemblyto fthe driven -shaft -I 9. v

Thehandle.; II carrieswires 2 1li-forl delivering electrical energy to.-the-frriotorfI3;r A.trigger.-type switcni 25 is.- mounted in the handle in such. a manner topermitlconvenient gripping and actu.- ating by thefoperator. Themotor I3ncomprises a-lstationary: eldwinding 26-` and a rotatable armature 2.11.- The armature'is. providedwitha vertically disposed shaft-28(1which .extends down through the. housing to the1 lowery portion-.containing thegear means I 5.

Thefgear means. I5 includes a small spur gear 29 on Athee lower end ofithemotordriven shafty 28 Whichrmeshes withza largergear 30.- The gear l30 isHcarried-onthe upperA end ofthe tool driving shaftl 49;. Aninner geancasingSI carries'a bearing 32of theballtype which supports the. motor shaft 28.v The. upper: end of. the armature. or motor shaft28- is journaled in a bearing 33 lin the top of thehousing I0; The tool drivingshaft I9 isJjou-rnally. supported by spacedballlbearings .34 and 35..,whichflank thegear. 30 .onethe upper. and lower. sides respectively The bearing. 35.. is mounted in a bushing 3.6. which isthreadedly re.- movable. from.the. lower. endof the. housing I0 asshown at'3'l. Accessmaybehad tothe interior o.- thegear. housing v3.I.by. removing the bushing 36. It` should be. understood. that: anyA desired gearing arrangement. .maybeemployed. In `the arrangementshown .the speed .ofthe sandingtool I6. is..consic'ieraloly.` reduced through the driving fromithe smallgear- 29.-to the large gearA 30.

A partitionv 38 partially encloses the motorA I3 inithe upper portion I2 ofthe. housing Ill; This partition 38 has-.farlarge central-openingwhich permits? and; provides; for. passage between.A the motor. portionof the housing andrthat portion of.Y the-housing I0 s positionedbetween the.- motor andthe gear: means. Thiscentral'sectionof, the housing is:- designated'.4 by the.; numeral 38 and 3 may be termed a fan housing as it encloses a fan 40 shown in detail in Figure 5,. The housing IU is circular at its top, and' at the position of the fan 4|) it is substantially triangular with three identical sides and adjoining vertices. The fan housing 39 is provided with similar openings 4| f` and armature and at approximately the-level of the motor commutator 52.

The fan 40 is provided with a solid disc back 43 andvcarries radially disposed fan blades 44 spaced and weldedor otherwise attached at regular intervals around the top surface thereof. The bottom of the disc 43 is equipped with a centrally located hub 45 which'is'mounted on the -motor driven shaft 28 .and held for rotation with i the shaft by a pin or the like .46. The fan thus rotates upon operation of the motor |3, and as it impels air outwardly through the openings 4|, it draws in cool air through the top openings 42 causing a continual passage of'cooling air over the motor, thus maintaining it relatively cool. The solid backed fan forms a partition between the fan housing and gear housing and thus prevents drawing of air from the gear housing i4 in the same manner as air is drawn over the motor. 'I'his avoids creating a suction or partial `vacuum in the gear housing and also an added motor load. An open backed fan would put considerable drag on the motor.

The fan housing and the gear case comprise in which accelerated air discharge is obtained will be most easily understood by reference to Figure 5, from which it will be apparent that the lugs 49 are arranged with their inclined end walls 41 lying in the curve of 4a spiral 52 extending outwardly from the inner ends of the fan blades 44. The inner walls 53 of the lugs 49 are also of spiral form, lying in the curve of a spiral 54 extending outwardly from the periphery of the fan. The point of intersection'of the spirals l52 and54 is just outside of the diameter of the fan, so that the lugs 45 may be of ample cross section to hold the gear housing and tool and to accommodate the screws 48, yet the flow of air from the, fan is substantially unrestricted. Thus, a maximum volume of air is moved through the motor with a minimum expenditure of power.

As best shown in Figure 4, the bushing 36 is provided with diametrically opposed recesses i? and 5| in the lower surface thereof for engagement by a tool to effect easy removal thereof from the inner gear casing 3|. It is t0 be noted, by referring to Figure 5, that the spirals or curved walls 52 and 53 form diverging air passages extending substantially transversely of the housing.

In operation, the portable power-driven tool causing the motor to rotate the sanding or buff- As seen in Figure 3, the l ing head I6 through the gear means l5. The motor is maintained cool by the fan drawing air `in through top openings 42 down over the motor and out through the streamlined shaped openings 4|. These openings 4| are guarded by rigid wires 5| positioned around and within each of the openings to prevent undesired tampering and also accidental injuries.

Numerous details of construction may be varied throughout a wide range without departing from the principles disclosed herein, and I therefore do not propose limiting the patent granted hereon otherwise than as necessitated by the appended claims.

What is claimed is:

1. In a portable power-driven rotatable tool comprising a vertically disposed housing having spaced openings therein near the top and central portions, an electric motor positioned within the top portion of the housing and .substantially between the spaced openings, said electric motor having a driven shaft extending downwardly in vsaid housing, a motor cooling fan mounted on said driven shaft and positioned adjacent the openings near the central portion of the housing,

whereby a current of air is drawn in through the top openings down over the electric motor and thrown outwardly through the central passages by the motor cooling fan, and gear means associated with the lower end of said driven shaft and said tool for imparting rotation thereto, said housing at its central portion having an external triangular shape with supporting bosses at the triangle vertices, said bosses having curved inner and outer surfaces to provide a plurality of diverging air passages of spiral shape extending substantially transversely of said fan shaft whereby'air discharged therefrom is directed from the housing between said surfaces.

2. In a power-driven tool comprising a housing having spaced openings therein, a motor positioned in one end of said housing substantially between said housing openings, and a tool carried in Ythe other end of the housing, means connecting the motor and the tool fo-r imparting motor drive to the tool, a motor cooling fan positioned adjacent one of said housing openings and rotatable with said motor for drawing air in through the other of said openings over the motor and out of the openings adjacent the fan, said housing having a plurality of bosses spaced apart from each other around said fan for supporting said connecting means, said bosses having curved inner and outer surfaces to provide a plurality of diverging air passages of spiral shape extending substantially transversely of `said housing whereby air discharged therefrom is directed frornthe housing between said surfaces.

3. n a power-driven tool having a housing with spaced openings therein, an electric motor in one end of the housing and a tool carried in the other end, gear means intermediate the motor and the tool, a fan positioned adjacent some of said spaced openings and between said motor and gear means, whereby a current of air is drawn in said housing through other of said openings down over the motor and thrown outwardly ythrough said some openings, said fan having a solid back pate next to said gear means for shielding said gear means from the action of the fan, said housing at the position of `said fan having an external triangular shape with bosses for supporting said gear means at the triangle vertices, said bosses having curved inner and outer Surfaces to provide a plurality of diverging air 5 passages of spiral shape extending substantially transversely of said housing whereby air discharged therefrom is directed from the housing between said surfaces.

KENNETH C. ATKIN.

REFERENCES CITED The following references are of record in the le of this patent:

Number 6 UNITED STATES PATENTS Name Date Poth Feb. 10, 1925 Albertson May 4, 1937 Mitchell June 6, 1944 Scoeld Sept. 5, 1944 

